HWD,
I don't have a bad word to say about Farnborough, but sometimes I do get a bit of a shock when they've given me a squawk (and one would therefore typically presume they're watching me blip across some screen somewhere) and they don't call me with traffic which I would really prefer to know about (EGLK<->CPT between 2000 and 2500 being a prime example).
I'm not complaining at all, they really are the most friendly and helpful bunch you could ask for! But it's caveat emptor out there - it doesn't matter how they dress it up (with a squawk), you're still only buying a best-endeavours FIS.
Rgds,
TPK